glib/giroffsets.c
2009-02-12 01:32:25 -02:00

544 lines
13 KiB
C

/* GObject introspection: Compute structure offsets
*
* Copyright (C) 2008 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "girffi.h"
#include "girnode.h"
/* The C standard specifies that an enumeration can be any char or any signed
* or unsigned integer type capable of resresenting all the values of the
* enumeration. We use test enumerations to figure out what choices the
* compiler makes.
*/
typedef enum {
ENUM_1 = 1 /* compiler could use int8, uint8, int16, uint16, int32, uint32 */
} Enum1;
typedef enum {
ENUM_2 = 128 /* compiler could use uint8, int16, uint16, int32, uint32 */
} Enum2;
typedef enum {
ENUM_3 = 257 /* compiler could use int16, uint16, int32, uint32 */
} Enum3;
typedef enum {
ENUM_4 = G_MAXSHORT + 1 /* compiler could use uint16, int32, uint32 */
} Enum4;
typedef enum {
ENUM_5 = G_MAXUSHORT + 1 /* compiler could use int32, uint32 */
} Enum5;
typedef enum {
ENUM_6 = ((guint)G_MAXINT) + 1 /* compiler could use uint32 */
} Enum6;
/* GIrNodeValue has guint32 values, so if it matters to the ABI whether
* constant values are signed, we are in trouble. And we don't handle
* enums with > 32 bit values. */
#if 0
typedef enum {
ENUM_7 = -1 /* compiler could use int8, int16, int32 */
} Enum7;
/* etc... */
#endif
static void
compute_enum_storage_type (GIrNodeEnum *enum_node)
{
GList *l;
guint32 max_value = 0;
int width;
if (enum_node->storage_type != GI_TYPE_TAG_VOID) /* already done */
return;
for (l = enum_node->values; l; l = l->next)
{
GIrNodeValue *value = l->data;
if (value->value > max_value)
max_value = value->value;
}
if (max_value < 128)
width = sizeof (Enum1);
else if (max_value < 256)
width = sizeof (Enum2);
else if (max_value < G_MAXSHORT)
width = sizeof (Enum3);
else if (max_value < G_MAXUSHORT)
width = sizeof (Enum4);
else if (max_value < G_MAXINT)
width = sizeof (Enum5);
else
width = sizeof (Enum6);
if (width == 1)
enum_node->storage_type = GI_TYPE_TAG_UINT8;
else if (width == 2)
enum_node->storage_type = GI_TYPE_TAG_UINT16;
else if (width == 4)
enum_node->storage_type = GI_TYPE_TAG_UINT32;
else if (width == 8)
enum_node->storage_type = GI_TYPE_TAG_UINT64;
else
g_error ("Unexpected enum width %d", width);
}
static gboolean
get_enum_size_alignment (GIrNodeEnum *enum_node,
gint *size,
gint *alignment)
{
ffi_type *type_ffi;
compute_enum_storage_type (enum_node);
switch (enum_node->storage_type)
{
case GI_TYPE_TAG_INT8:
case GI_TYPE_TAG_UINT8:
type_ffi = &ffi_type_uint8;
break;
case GI_TYPE_TAG_INT16:
case GI_TYPE_TAG_UINT16:
type_ffi = &ffi_type_uint16;
break;
case GI_TYPE_TAG_INT32:
case GI_TYPE_TAG_UINT32:
type_ffi = &ffi_type_uint32;
break;
case GI_TYPE_TAG_INT64:
case GI_TYPE_TAG_UINT64:
type_ffi = &ffi_type_uint64;
break;
default:
g_error ("Unexpected enum storage type %s",
g_type_tag_to_string (enum_node->storage_type));
}
*size = type_ffi->size;
*alignment = type_ffi->alignment;
return TRUE;
}
static gboolean
get_interface_size_alignment (GIrNodeType *type,
GIrModule *module,
GList *modules,
gint *size,
gint *alignment,
const char *who)
{
GIrNode *iface;
GIrModule *iface_module;
if (!g_ir_find_node (module, modules, type->interface, &iface, &iface_module))
{
g_warning ("Can't resolve type '%s' for %s", type->interface, who);
*size = -1;
*alignment = -1;
return FALSE;
}
g_ir_node_compute_offsets (iface, iface_module,
iface_module == module ? modules : NULL);
switch (iface->type)
{
case G_IR_NODE_BOXED:
{
GIrNodeBoxed *boxed = (GIrNodeBoxed *)iface;
*size = boxed->size;
*alignment = boxed->alignment;
break;
}
case G_IR_NODE_STRUCT:
{
GIrNodeStruct *struct_ = (GIrNodeStruct *)iface;
*size = struct_->size;
*alignment = struct_->alignment;
break;
}
case G_IR_NODE_OBJECT:
case G_IR_NODE_INTERFACE:
{
GIrNodeInterface *interface = (GIrNodeInterface *)iface;
*size = interface->size;
*alignment = interface->alignment;
break;
}
case G_IR_NODE_UNION:
{
GIrNodeUnion *union_ = (GIrNodeUnion *)iface;
*size = union_->size;
*alignment = union_->alignment;
break;
}
case G_IR_NODE_ENUM:
case G_IR_NODE_FLAGS:
{
return get_enum_size_alignment ((GIrNodeEnum *)iface,
size, alignment);
}
case G_IR_NODE_CALLBACK:
{
*size = ffi_type_pointer.size;
*alignment = ffi_type_pointer.alignment;
break;
}
default:
{
g_warning ("%s has is not a pointer and is of type %s",
who,
g_ir_node_type_to_string (iface->type));
*size = -1;
*alignment = -1;
break;
}
}
return *alignment > 0;
}
static gboolean
get_type_size_alignment (GIrNodeType *type,
GIrModule *module,
GList *modules,
gint *size,
gint *alignment,
const char *who)
{
ffi_type *type_ffi;
if (type->tag == GI_TYPE_TAG_ARRAY)
{
gint elt_size, elt_alignment;
if (!type->has_size
|| !get_type_size_alignment(type->parameter_type1, module, modules,
&elt_size, &elt_alignment, who))
{
*size = -1;
*alignment = -1;
return FALSE;
}
*size = type->size * elt_size;
*alignment = elt_alignment;
return TRUE;
}
else if (type->is_pointer)
{
type_ffi = &ffi_type_pointer;
}
else
{
if (type->tag == GI_TYPE_TAG_INTERFACE)
{
return get_interface_size_alignment (type, module, modules, size, alignment, who);
}
else
{
type_ffi = g_ir_ffi_get_ffi_type (type->tag);
if (type_ffi == &ffi_type_void)
{
g_warning ("%s has void type", who);
*size = -1;
*alignment = -1;
return FALSE;
}
else if (type_ffi == &ffi_type_pointer)
{
g_warning ("%s has is not a pointer and is of type %s",
who,
g_type_tag_to_string (type->tag));
*size = -1;
*alignment = -1;
return FALSE;
}
}
}
g_assert (type_ffi);
*size = type_ffi->size;
*alignment = type_ffi->alignment;
return TRUE;
}
static gboolean
get_field_size_alignment (GIrNodeField *field,
GIrNode *parent_node,
GIrModule *module,
GList *modules,
gint *size,
gint *alignment)
{
gchar *who;
gboolean success;
who = g_strdup_printf ("field %s.%s.%s", module->name, parent_node->name, ((GIrNode *)field)->name);
success = get_type_size_alignment (field->type, module, modules, size, alignment, who);
g_free (who);
return success;
}
#define ALIGN(n, align) (((n) + (align) - 1) & ~((align) - 1))
static gboolean
compute_struct_field_offsets (GIrNode *node,
GList *members,
GIrModule *module,
GList *modules,
gint *size_out,
gint *alignment_out)
{
int size = 0;
int alignment = 1;
GList *l;
gboolean have_error = FALSE;
*alignment_out = -2; /* mark to detect recursion */
for (l = members; l; l = l->next)
{
GIrNode *member = (GIrNode *)l->data;
if (member->type == G_IR_NODE_FIELD)
{
GIrNodeField *field = (GIrNodeField *)member;
if (!have_error)
{
int member_size;
int member_alignment;
if (get_field_size_alignment (field, node,
module, modules,
&member_size, &member_alignment))
{
size = ALIGN (size, member_alignment);
alignment = MAX (alignment, member_alignment);
field->offset = size;
size += member_size;
}
else
have_error = TRUE;
}
if (have_error)
field->offset = -1;
}
else if (member->type == G_IR_NODE_CALLBACK)
{
size = ALIGN (size, ffi_type_pointer.alignment);
alignment = MAX (alignment, ffi_type_pointer.alignment);
size += ffi_type_pointer.size;
}
}
/* Structs are tail-padded out to a multiple of their alignment */
size = ALIGN (size, alignment);
if (!have_error)
{
*size_out = size;
*alignment_out = alignment;
}
else
{
*size_out = -1;
*alignment_out = -1;
}
return !have_error;
}
static gboolean
compute_union_field_offsets (GIrNode *node,
GList *members,
GIrModule *module,
GList *modules,
gint *size_out,
gint *alignment_out)
{
int size = 0;
int alignment = 1;
GList *l;
gboolean have_error = FALSE;
*alignment_out = -2; /* mark to detect recursion */
for (l = members; l; l = l->next)
{
GIrNode *member = (GIrNode *)l->data;
if (member->type == G_IR_NODE_FIELD)
{
GIrNodeField *field = (GIrNodeField *)member;
if (!have_error)
{
int member_size;
int member_alignment;
if (get_field_size_alignment (field, node,
module, modules,
&member_size, &member_alignment))
{
size = MAX (size, member_size);
alignment = MAX (alignment, member_alignment);
}
else
have_error = TRUE;
}
}
}
/* Unions are tail-padded out to a multiple of their alignment */
size = ALIGN (size, alignment);
if (!have_error)
{
*size_out = size;
*alignment_out = alignment;
}
else
{
*size_out = -1;
*alignment_out = -1;
}
return !have_error;
}
static gboolean
check_needs_computation (GIrNode *node,
GIrModule *module,
gint alignment)
{
/*
* 0: Not yet computed
* >0: Previously succeeded
* -1: Previously failed
* -2: In progress
*/
if (alignment == -2)
{
g_warning ("Recursion encountered when computing the size of %s.%s",
module->name, node->name);
}
return alignment == 0;
}
/**
* g_ir_node_compute_offsets:
* @node: a #GIrNode
* @module: Current module being processed
* @modules: all currently loaded modules
*
* If a node is a a structure or union, makes sure that the field
* offsets have been computed, and also computes the overall size and
* alignment for the type.
*/
void
g_ir_node_compute_offsets (GIrNode *node,
GIrModule *module,
GList *modules)
{
switch (node->type)
{
case G_IR_NODE_BOXED:
{
GIrNodeBoxed *boxed = (GIrNodeBoxed *)node;
if (!check_needs_computation (node, module, boxed->alignment))
return;
compute_struct_field_offsets (node, boxed->members,
module, modules,
&boxed->size, &boxed->alignment);
break;
}
case G_IR_NODE_STRUCT:
{
GIrNodeStruct *struct_ = (GIrNodeStruct *)node;
if (!check_needs_computation (node, module, struct_->alignment))
return;
compute_struct_field_offsets (node, struct_->members,
module, modules,
&struct_->size, &struct_->alignment);
break;
}
case G_IR_NODE_OBJECT:
case G_IR_NODE_INTERFACE:
{
GIrNodeInterface *iface = (GIrNodeInterface *)node;
if (!check_needs_computation (node, module, iface->alignment))
return;
compute_struct_field_offsets (node, iface->members,
module, modules,
&iface->size, &iface->alignment);
break;
}
case G_IR_NODE_UNION:
{
GIrNodeUnion *union_ = (GIrNodeUnion *)node;
if (!check_needs_computation (node, module, union_->alignment))
return;
compute_union_field_offsets (node, union_->members,
module, modules,
&union_->size, &union_->alignment);
break;
}
case G_IR_NODE_ENUM:
case G_IR_NODE_FLAGS:
{
GIrNodeEnum *enum_ = (GIrNodeEnum *)node;
if (enum_->storage_type != GI_TYPE_TAG_VOID) /* already done */
return;
compute_enum_storage_type (enum_);
break;
}
default:
/* Nothing to do */
return;
}
}